Many modern security camera systems have illumination systems for illuminating the scene from which the security camera captures images. Often, these illumination systems are activated at night so that parking lots or darkened hallways can be monitored even in the absence of other light sources.
It is also common that these security camera illumination systems used infrared diodes to illuminate the scene. Diodes are very power efficient. And, the use of infrared light illumination ensures that the cameras do not have a detrimental effect on individuals within the scene. The use of infrared illumination also reduces the obtrusiveness and visibility of the security camera systems.
Generally, to minimize the power consumed by the security camera systems and to provide optimal imaging conditions, the power to the illumination systems is controlled based on available light. As a result, if only moderate supplemental illumination is required, then the illumination systems of the security camera systems will only be operated at low power. Other times when the power to the illumination systems should be controlled are when the scene imaged by the security camera systems changes such that there are objects that are closer to the security camera or are possibly more reflective of infrared light. In these cases, the power to the illumination systems should be reduced to avoid saturating the imaging sensors or chips within the security camera systems that captures the frames of the scene.
Some security camera systems include photo sensors that detect light reflected from the scenes and then controllers of the security camera systems control the power to the illumination systems based on this reflected light. As result, when an object moves close to the security camera and reflects excessive light from the illumination system back into the imaging sensor, this reflected tight is detected by the photosensor. The controller then reduces the power to the illumination system.